The present invention relates to a high-quality titanium target for sputtering which is free from the generation of fractures and cracks during high-power sputtering (high-rate sputtering) and is capable of stabilizing the sputtering characteristics.
The impurity concentration described in the present specification will be displayed in mass fraction (mass percent or ppm) in all cases.
In recent years, various electronic devices have been devised beginning with the exponential advancement of semiconductors, and the improvement of the performance thereof as well as the development of new devices are being sought on a daily basis.
Under these circumstances, there is an inclination toward the miniaturization of electronic devices and equipment and increase in the degree of integration thereof. Various thin films are formed during the manufacturing process of many of such devices and equipment, and titanium, from its unique metallic property, is used in the formation of thin films for various electronic devices as titanium and its alloy film, titanium silicide film, titanium nitride film or the like.
Generally speaking, the aforementioned titanium and its alloy film, titanium silicide film or titanium nitride film can be formed with a physical deposition method such as sputtering or vacuum deposition. Explained below is the sputtering method which is used most comprehensively among the above.
This sputtering method is a method of physically colliding positive ions such as Ar+ to a target disposed on a cathode and discharging the metal atoms structuring the target with the collision energy thereof. Nitrides can be formed by using titanium or its alloy (TiAl alloy, etc.) as the target and conducting sputtering under a mixed gas atmosphere of argon gas and nitrogen.
In recent years, in order to improve the production efficiency, there are demands for high-rate sputtering (high-power sputtering). Here, there are cases where the target is subject to fractures or cracks, and this has caused a problem of preventing stable sputtering. Patent Document 1 and Patent Document 2 listed below are cited as prior art documents.
Moreover, as shown in Patent Document 3, the present Applicant provided a titanium target for sputtering which is free from fractures and cracks during high-power sputtering (high-rate sputtering) and is capable of stabilizing the sputtering characteristics. While this is extremely useful for achieving the foregoing object, there were demands for achieving superior effects with fewer types of additive elements and a smaller additive amount for use in a high-purity sputtering target for semiconductors, and this point was an additional challenge.
Patent Document 1: International Publication No. WO01/038598
Patent Document 2: JP 2001-509548 A
Patent Document 3: JP 2010-235998 A